Det Insp Nevin Hunter, head of the NWCU, said: "The odd guy going and poaching the odd deer is probably less serious to deal with than the person involved who is part of a gang that is going around and systematically taking large numbers of animals and threatening people on farms.

"What we do know is that people will travel all around the country involved in illegal poaching."

Experts say the worst hit area of the country is Exmoor National Park on the Devon and Somerset border, where seven stags were recently found butchered and decapitated.

PC Martin Beck, wildlife crime officer for Devon and Cornwall Police, said poachers sell their venison to "unscrupulous butchers, game dealers and pubs and restaurants looking for meat through the back door".

He added: "It is not just one for the pot any more, these are organised people making money. They have a network of people, who can get together quite quickly on a certain night, to go out.

"They know what they are doing, they are going out to purposefully take the meat and they know how to get rid of it to make money.

"These people will protect themselves, some of the people are linked to other crimes and some of those crimes do involve violence."

National Trust head ranger for west Exmoor, Julian Gurney, fears poaching is damaging the national park's red deer population.

He said: "Every autumn, I hear the roar that the stags make while the rut is on. I should, and have, heard stags, every day, and I have only heard one this year – that is very unusual.

"I may be in the wrong place at the wrong time, but that has never happened before."

It is not illegal to shoot deer in daylight but hunters need permission from landowners and licenses for their firearms.

Penalties for illegal poaching include fines and a three-month prison sentence.